The Value Of Adrenal Volume In Differentiating Idiopathic Aldosteronism From Aldosterone-producing Adenoma

Background and ObjectiveAs the most common cause of secondary hypertension,primary aldosteronism(PA)is a common disease of the endocrine system,which has received increasing attention in recent years.PA is a disease featuring as hypersecretion of aldosterone,and relatively independent of angiotensin?,plasma potassium concentration and other major aldosterone secretion regulators as well as the amount of sodium.This inappropriate aldosterone secretion can lead to plasma renin inhibition,hypertension,sodium retention and hypokalemia.The harm of PA is not only hypertension,but also the special toxicity of aldosterone hormone.Several studies have confirmed that the risk of heart diseases(coronary heart diseases,left ventricular hypertrophy,heart failure),stroke,kidney diseases,metabolic syndrome,type 2 diabetes and bone diseases are higher in patients with PA compared to patients with essential hypertension matched by age,sex and blood pressure.Idopathic hyperaldosteronism(IHA)and aldosterone-producing adenoma(APA)are the two most common subtypes of PA,covering more than 90%in total.The etiology of PA determines its best treatment.APA patients are advised to undergo unilateral adrenalectomy,however,for IHA patients,the benefit of surgery is limited.Therefore,the treatment of mineralcorticoid receptor antagonist(MRA)is recommended.Both treatments can prevent end-stage PA(i.e.end-stage renal disease and irreversible cardiovascular damage).The distinguish of IHA and APA is crucial.AVS is considered to be the gold standard for subtype differentiation at present,but it is invasive and technically demanding,in addition,the right adrenal vein is thin and deep,which requires highly experienced experts to carry out,so it is difficult to apply widely.Moreover,the specific pointcut of the AVS is still controversial.Therefore,exploring another non-invasive classification method is very necessary.The purpose of this study is providing basis for the classification and diagnosis of PA by measuring the adrenal volume using MSCT.MethodsThe patients with PA and essential hypertension diagnosed in the Department of Endocrinology,the First Affiliated Hospital of Zhengzhou University from 2017 to2018 were selected as the subjects in this study.The inclusion criterias of PA were as follows:(1)ARR>30 ng/dL[ng/(mL·h)]),PAC?15 ng/dl,and confirmed by diagnostic tests(captopril inhibition test and/or saline infusion test)as PA;(2)Enhanced MSCT scan of adrenal gland were performed.Inclusion and grouping criterias of IHA and APA:Patients confirmed as PA without any evidence of lateralized PAC overdose were included in the IHA group;and those without such evidences were included in the APA group(lateralized aldosterone overdose evidences:lateralization of PAC secretion during AVS;lateralization of PAC secretion during surgery;adrenal adenoma confirmed by pathology;recovery or improvement of blood pressure after adenectomy).The dominant secretion of PAC on the left side would put to the LAPA group,and the dominant secretion of PAC on the left side would put to the RAPA group.The inclusion criterias of the essential hypertension control group were as follows:(1)Secondary hypertension was excluded after a comprehensive evaluation and diagnosed as essential hypertension;(2)Adrenal diseases were excluded by enhanced MSCT scan of adrenal gland.The exclusion criterias of all subjects were as follows:(1)age:<18 or>70years old;(2)hydronephrosis,splenomegaly,cirrhosis and other diseases affecting the position or volume of adrenal gland;(3)abdominal surgery history;(4)pregnancy or lactation;(5)oral contraceptive or estrogen hormone replacement therapy;(6)severe heart failure,renal failure and other organ dysfunction;(7)malignant tumors;(8)other secondary hypertension;(9)incomplete clinical data.Finally,a total of 92 subjects were included.The clinical data of all subjects were collected.The MEDICAL SYSTEMS machine of GE company performed enhanced MSCT scan of adrenal gland,and the volume of adrenal gland was reconstructed and calculated by CT semi-automatic segmentation method in IntelliSpace Portal V8 post-processing workstation of Philips.It was double-blind delineated by two independent radiologists,and the average value was taken as the final figure.Results1 A total of 92 subjects(45 males,48.91%),aged(44.04±10.31)years,were included in this study.Compared with control group,ARR,24-hour urinary PAC,left adrenal volume,right adrenal volume and total adrenal volume were increased and serum potassium was decreased in PA group(P<0.05).2 There were significant differences in ARR,24-hour urinary aldosterone,total adrenal volume and serum potassium among APA group,IHA group and control group(P<0.01).Further comparison shows that there were significant differences in ARR,24-hour urinary aldosterone,serum potassium and total adrenal volume between the control group and the APA group,as well as between the control group and the IHA group(P<0.05).Compared with IHA group,ARR and 24-hour urinary PAC were higher and serum potassium was lower in APA group(P<0.05),however,the total adrenal volume showed no difference(P=0.26).3 There were significant differences in left adrenal volume,right adrenal volume and total adrenal volume among four groups(P<0.01).Further comparison showed that the volume of any adrenal gland was higher in IHA group than that in control group(P<0.05).The ipsilateral side's volume of APA was higher than that in IHA group and control group(P<0.05).The APA's contralateral side volume of adrenal gland showed no significant difference in the control group(left P=0.309,right P=0.088)and IHA group(left P=0.136,right P=0.149).4 The difference of adrenal volume differed between the four groups(P<0.01).When further comparison,there was no significant difference between the control group and IHA group(P=0 808),while other groups differed(P<0.05).5 The increase of total adrenal volume had a good predictive value for PA,AUC was 0.811.The best cut-off point was 8.61cm~3,the sensitivity,specificity and Jordan index for predicting PA were 0.738,0.806 and 0.544,respectively.Conclusion1 The total adrenal volume of PA patients is increased,which can predicte PA.2 The volume difference of bilateral adrenal glands may differentiate APA from IHA.